Process for removing vanadium from iron ores



United States Patent ABSTRACT OF THE DISCLOSURE This invention relates to a process for removing the vanadium values from a vanadium bearing iron ore. The process comprises roasting the ore in a two-step operation in the presence of an alkali metal salt and subsequently water leaching the roasted ore to obtain a high yield of the vanadium values in soluble form in the leach liquor.

BACKGROUND THE INVENTION Many roasting and leaching methods are well-known in the prior art for removing the vanadium values from a vanadium bearing iron ore.

In most of the prior art processes, however, the recovery of the vanadium values in the leach liquor is lower than desired.

SUMMARY OF THE INVENTION In the instant process high vanadium recoveries are obtained from vanadium bearing iron ore. The ore is admixed with an alkali metal compound and formed into pellets or nodules and roasted in a two step heating operation to form the maximum amount of water soluble alkali metal vanadate in the pellet and upon leaching high recoveries of the vanadium values are obtained in the leach liquor.

The roasted pellets may be leached with or without crushing. In either case the vanadium recoveries are very high. If the roasted ore pellets are leached without crushing, the leached pellets are strong enough to be added to a blast furnace operation without crumbling.

These advantageous effects are obtained by the instant process which comprises admixed finely divided vanadium bearing iron ore with an alkali metal compound selected from the group consisting of sodium and potassium, and pelletizing the same, subjecting the pelletized mixture to an oxidizing heat treatment to temperature from 7 00 F. to 1950 F. to oxidize and harden the pellets, then further subjecting the pellets to an additional heat treatment at 2200 F. to 2450 F. to further harden or sinter the pellets and to form the maximum amount of a water soluble alkali metal vanadate in the pellets, leaching the roasted material with water at '140" F. to 180 F; to solubilize the alkali metal vanadate values.

DESCRIPTION OF THEIREFERRED H EMBODIMENT In carrying out the instant process, the vanadium bear-'- 3,486,842 Patented Dec. 30, 1969 sodium sulfate and sodium chloride are particularly useful for economic reasons.

The pellets when formed usually contain about 5 to 15% water. After drying, the pellets are then heated under oxidizing conditions at a temperature from 700 F. to 1950 F. to oxidize and to harden the pellet so that they can be introduced into a high temperature furnace, such as a shaft, furnace, without crumbling. The time of the oxidizing heat treatment should be at least 15 minutes at 700 F. or at least 5 minutes at 1950 F. Times of .heating up to two hours are not detrimental except for economy reasons. Although this oxidizing and heating operation may be carried out in many typesof apparatus, a particularly useful type is one in which the pellets are placed on a moving grate and are oxidized by passing a blast of heated air or oxidizing gases through the moving grate.

After the pellets .have been oxidized and hardened, they are then further heated to a temperature from 2200 F. to 2450" F. and held at that temperature for at least 30 minutes. During this treatment, the pellets are further hardened or sintered and at the same time the maximum amount of the water soluble alkali metal vanadate compound is formed in the pellets.

After cooling the hardened pellets with or without crushing, they are leached thoroughly with water to form an alkali metal vanadate leach liquor.

In order to describe more fully the instant invention the following examples are presented:

EXAMPLE 1 A magnetite iron ore concentrate containing 0.43% vanadium on an ore weight basis, was wet ground to minus 325 mesh. The ground ore was filtered and the filter cakecontained about 10% water. Sodium carbonate equivalent to three percent by weight on a dry ore basis was added to the moist filter cake and the mixture was rolled in a mixer to form nodules or pellets. The pellets were screened and the inch to inch size were recovered, the over-size and under-size returned until the entire amount fell within the size range recited above.

These pellets were then placed in a drying oven and dried at 230 F. After drying they were then heated to 1000 F. in a current of heated air and held at that temperature for 15 minutes.

At the end of this oxidizing heat treament the pellets were introduced into a furnace where they were immediately .heated to 2420 F. and the pellets were sintered to form firm lumps.

. These sintered lumps were then crushed through a 20 mesh screen and leached thoroughly with water at 180 F. The leached residue was analyzed for vanadium and it was found that 88.4% of the vanadium values a had been removed.

EXAMPLES 2 -5 In Examples 2-5 the procedures of Example ltwas repeated except that'diiferent temperatures and times were usedfor the oxidizing heat treatments.

EXAMPLES 6-9 In Examples 69 various compounds of sodium were usedin varying amounts on several ores, and the pellets were leached whole, not crushed. In these examples the The amount of alkali metal compound employed may vary considerably however it has been found that amounts from 2% to 5% on an ore weight basis are particularly satisfactory.

Any alkali metal compound of sodium and potassium may be employed. Since sodium compounds are usually cheaper than potassium compounds, sodium carbonates,

EXAMPLES 10-13 In these examples various compounds of sodium and 4 What I claim is: e 1. Process for removing vanadium from iron ores which comprises admixing finely divided vanadium bearing magnetite iron ore with 2% to by weight of an alkali metal compound selected from the group consisting of potassium were used in varying amounts. The procedure 5 Sodium Carbonate, Sodium Sulfate, Sodium chloride, P of the preceding examples was followed except that intassium carbonate, potassium sulfate and potassium chlostead of pelletizing the mixture of ore and sodium or ride and p l g the Same subjecting the Pelletized potassium salt, it wa pressed into waf r o e in h in mixture to an oxidizing heat treatment at temperature diameter and about one quarter of an inch thick. These from 700 F. to 1950 F. to oxidize and harden the wafers were heated and leached in accordance with the pellets, the time of heat treatment being at least minprocedures of the previous examples as indicated in the ites When a temperature of 700 F. is employed and the table. heat treatment time being at least 5 minutes when 1950 In order to show the advantages obtained using the F. is empl y th n further subjecting the pellets to an process of the instant invention over the prior art sinter- 15 dditional heat treatment at 2200 F. to 2450 F. to ing processes, the following example is presented as a inter the pellets and to form the maximum amount of prior art control run. a water soluble alkali metal vanadate in said pellets, the time of the additional heat treatment being at least 30 EXAMPLE 14 minutes at 2200 F. to 2450 F., leaching the roasted In thls example the Pellets Were P p in the Same material with water to solubilize the alkali metal vanamanner as that described in Example 1 except that the date values dned Pellets were added d1recfly to a commerclal f 2. Process according to claim 1 in which the amount pellet shaft furnace Wlthout any preheatmg or oxldlz' of alkali metal compound admixed with the finely divided ing treatment. The pellets were brought to peak temperore to for th 11 t i f 27 t b ht ature almost immediately and after passing through the 6 PC e s 5 mm 0 o 0 y welg on furnace were recovered and leached with water in the an Ore basls same manner as that previously described. In this partic- Process f g to damn I m whlch the alkah ular control run the vanadium recovery was only 721% metal compound 13 scfdlum which clearly shows that the preheating or oxidizing step Process according to elalm 1 Whleh the alkall of the instant invention is necessary to obtain high vametal compound is Potassium eafbenate nadium recoveries. The operational details and the results PI'OCeSS according to Claim 1 n Whi h the roasted obtained are recorded in the following table. pellets are leached in water without crushing.

TABLE Examples A. 1 2 3 4 5 I 6 7 Ore, percent vanadium 0.43---. 0.43- 0.43.-- 0.43-.- 0.46--- 0.52.-- 0.54. l l ll metal compound used N51200:; NagOOa NaiCOa NazOOa NBQCO: NazCO; NagCo Percent on ore basis 3 3 3 3 3. 2 Oxidizing heat treatment:

Temp, 8 0 8001,670- 8001,670.

Water leaching:

Pellets whole or crushed Crushed Crushed. Time, hrs .0 1.0 Temp., F 18 140-180 Vanadium recovered in leach liquor, 88.4 90.7

percent.

Examples 8 9 10 11 12 13 14 Control run Ore, percent vanadium 0.52 0.43 0.54 0.54 0.54 0.54 0.43 Additive:

Alkali metal compound used N21200:"..- N8zCOa NaOl K 804 K200; KCl M20103..-" Percent on ore basis 4 5 i 5 oxidizing heat treatment Temp,, F 800-l,670- SOD-1,670---- 800-1,670 8001,670 SOD-1,670..-- BOO-1,670-.-- None Time, min 0 60 60 Final heat treatment:

Tem F 2,370 2,190 2,240 2,240 2,240 2,240 Time, min 60 120 60 60 60 60 Water leaching:

Pellets whole or cushed... Whole W Time, hrs 6.0-..- 4 Temp., F 180 Vanadium recovered in leach liquor, 90.5 86 0 percent.

References Cited UNITED STATES PATENTS 7/1966 Koerner et a1. 23-15 4/1968 Henrickson et a1.

U.S, c1, X,R. 

